Memory with deferred fractional row activation

ABSTRACT

Row activation operations within a memory component are carried out with respect to subrows instead of complete storage rows to reduce power consumption. Further, instead of activating subrows in response to row commands, subrow activation operations are deferred until receipt of column commands that specify the column operation to be performed and the subrow to be activated.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/065,278 filed Oct. 7, 2020 (now U.S. Pat. No. 11,270,741), which is acontinuation of U.S. application Ser. No. 16/528,523 filed Jul. 31, 2019(now U.S. Pat. No. 10,528,523), which is a continuation of U.S.application Ser. No. 15/889,191 filed Feb. 5, 2018 (now U.S. Pat. No.10,388,337), which is a continuation of U.S. application Ser. No.15/390,674 filed Dec. 26, 2016 (now U.S. Pat. No. 9,911,468), which is acontinuation of U.S. application Ser. No. 15/138,424 filed Apr. 26, 2016(now U.S. Pat. No. 9,570,126), which is a continuation of U.S.application Ser. No. 13/640,084 filed Oct. 9, 2012 (now U.S. Pat. No.9,330,735), which is a U.S. National Stage of International ApplicationNo. PCT/US2012/041758 filed Jun. 8, 2012, which claims priority to U.S.Provisional Patent Application No. 61/512,133 filed Jul. 27, 2011. Eachof the above-identified patent applications is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to the field of integratedcircuits, and more particularly to memory access operations withinintegrated-circuit memory devices.

BACKGROUND

Dynamic random access memories (DRAMs) are typically accessed in twophases. First, an address-specified page of data is transferred from arow of DRAM storage cells to a bank of sense amplifiers in a rowactivation operation. Thereafter, one or more column read or writeoperations are executed to retrieve or overwrite address-specifiedfractions (columns) of the page of data within the sense amplifier bank,thus reading or writing column data within the open page.

Row activation tends to be particularly time consuming, as low-amplitudesignals stored within individual storage cells are sensed via long,high-capacitance bit lines. To mitigate this timing bottleneck, DRAMshave traditionally been architected with relatively high row to columnratios (e.g., 64:1 or 128:1) to increase the likelihood thatback-to-back memory accesses will “hit” the same open page (i.e.,exploiting spatial/temporal locality), and thus enable multiplerelatively low-latency column operations per row activation.Unfortunately, the power expended to activate a given storage row islargely wasted as the vast majority of the data transferred to the senseamplifiers during row activation is untouched in ensuing columnoperations.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments disclosed herein are illustrated by way ofexample, and not by way of limitation, in the figures of theaccompanying drawings and in which like reference numerals refer tosimilar elements and in which:

FIG. 1 contrasts exemplary immediate-activation and deferred-activationmemory control modes;

FIG. 2A illustrates an exemplary transition from the deferred-activationcommand nomenclature of FIG. 1 to a row-load (L) and activate-read/write(AR) command nomenclature shown in later figures;

FIG. 2B presents a table of exemplary deferred-activation commands;

FIG. 3 illustrates the general format of exemplary open-page andclosed-page command sequences employing the deferred-activation commandsshown in FIG. 2B;

FIG. 4A illustrates an exemplary open-page, deferred-activation memoryprotocol within a synchronous memory system;

FIG. 4B illustrates an exemplary closed-page deferred-activationprotocol in which a command sequence directed to a given row and bank isconcluded by an activate-read-precharge command;

FIG. 5A illustrates an embodiment of a memory bank that may be employedwithin a multi-bank memory component to enable deferred-activationoperations;

FIG. 5B illustrates a progressed state of the memory bank of FIG. 5Afollowing receipt of an activate-read command within the host memorycomponent;

FIG. 5C illustrates a further progression in the state of the memorybank of FIG. 5A as a selected portion of the subpage data is conveyed toa column decoder via selected core I/O lines;

FIG. 5D illustrates a yet further progression in the state of the memorybank of FIG. 5A as data within another subpage data is conveyed to thecolumn decoder via selected core I/O lines;

FIG. 6A illustrates more detailed view of exemplary circuit blocks thatmay be used to implement the memory bank shown in FIGS. 5A-5C;

FIG. 6B illustrates embodiments of subpage activate circuits andSWL-select circuits that may be used to implement the subpage activatelogic and SWL-select segments shown in FIG. 6A;

FIG. 6C illustrates the state of memory bank architecture of FIG. 6Bfollowing receipt of a column command;

FIG. 7A illustrates a reduced-latency transaction protocol that may beimplemented by a controller component that is aware of (i.e., designedto assume or detect the presence of) the deferred activation,subpage-access memory component architecture described in reference toFIGS. 5A-5D and 6A-6C;

FIG. 7B illustrates another exemplary subpage-aware transaction protocolthat employs an auto-precharging activate-read command out of order withrespect to a non-precharging activate-read command;

FIG. 8 illustrates an alternative set of exemplary deferred-activationcommands that includes a pair of non-activating column commands, “Read”and “Read-Precharge.”

FIG. 9 illustrates closed-page and open-page access sequences supportedby a memory system that explicitly differentiates between activating andnon-activating column commands;

FIGS. 10A and 10B illustrate examples of open-page and closed-pagememory protocols, respectively, corresponding to theactivation-differentiated column command sequences shown in FIG. 9 ;

FIG. 11 illustrates three additional command types that may be supportedwithin a deferred-activation memory system, including an additional rowcommand and two additional activation-triggering column commands;

FIG. 12 illustrates additional open-page command sequences andtransitional command sequences made possible by the additionalload-precharge command and the pre-activation-delay column commandsshown in FIG. 11 ;

FIG. 13A illustrates an exemplary open-page memory protocol employing aload-precharge command;

FIG. 13B illustrates an alternative command sequence that employs aload-precharge command to reduce CA bandwidth consumption, and in whicheach subpage-activating column command triggers output of two bursts ofdata from respective address ranges;

FIG. 13C illustrates another exemplary open-page memory protocolemploying a load-precharge command followed by an auto-prechargingcolumn command and then a non-activating column command;

FIG. 13D illustrates another exemplary open-page memory protocolemploying a load-precharge command followed by a non-auto-prechargingprecharge-delay column command and then by a low-latency, non-activatingcolumn command;

FIG. 14 illustrates embodiments of a controller component and memorycomponent that may be used to implement the various deferred-activationcommand sequences and protocols described in reference to precedingfigures; and

FIG. 15 illustrates a sequence of configuration operations that may beexecuted by the controller component of FIG. 14 to enabledeferred-activation operations.

DETAILED DESCRIPTION

In various embodiments disclosed herein, row activation operationswithin a memory component are carried out with respect to fractions ofstorage rows or “subrows” instead of complete storage rows, therebysubstantially lowering activation power consumption. Further, instead ofexecuting subrow activation operations in response to row commands(i.e., commands bearing row address values), subrow activationoperations are deferred until receipt of column commands that specifythe column operation to be performed (e.g., read or write) and thesubrow to be activated. By this arrangement, sub-row address bits aredelivered within column commands where they naturally form part or allof the column address instead of being redundantly transmitted in rowcommands. Moreover, by pipelining deferred subrow activation operations,peak memory bandwidth remains uncompromised, and by re-timing columncommand transmission to immediately follow row command transmission, noor negligible additional access latency is incurred. Accordingly, withinvarious embodiments disclosed herein, deferred fractional row activationyields reduced power consumption without sacrificing command/addressbandwidth or peak memory bandwidth and with no or negligible accesslatency increase.

FIG. 1 contrasts two exemplary memory control modes supported by amemory controller according to embodiments disclosed herein. In animmediate-activation mode shown at 101, a row activation command 103(ACT BRx) directed to a given bank ‘B’ and storage row ‘Ra’ of a memorycomponent is transmitted via a command/address (CA) signaling path. Rowactivation is triggered in response to the row activation command (hencethe “immediate-activation” mode), with data from all storage cellsassociated with the specified row being transferred to a bank of senseamplifiers during row-activation interval t_(RCD). After the rowactivation interval has elapsed, a column access command 105 (RD BCa0)directed to the row-activated bank ‘B’ and bearing column address ‘Ca0’is transmitted via the CA signaling path (note that the row-activationand column read/write command sequences are shown in separate timingsequences, designated “CA-ROW” and “CA-COL” but may be nonethelesstransmitted via a shared set of CA signaling links) to trigger a columnaccess operation, in this case a column read operation (RD) in which therecipient memory device outputs a column of read data from the specifiedcolumn ‘Ca0’ of the open page (i.e., the row data within the senseamplifier bank) of the specified bank. Accordingly, after a columnaccess interval t_(CAC), read data, Q(BCa0) 106, is output via a set ofread/write data signaling links (DQ) over a t_(CC) interval (i.e.,minimum time between successive column operations within the memorycomponent). As shown, a second column read command 107 directed tocolumn ‘Cb0’ (i.e., bearing column address ‘Cb0’) is received a t_(CC)interval after the initial column read command and thus yields read dataoutput Q(BCb0) 108 a t_(CAC) interval later. Similarly, a second rowcommand 113 is received a t_(RR) interval after row command 103 to beginrow activation in another bank of the memory component and thus maintainpeak data transfer bandwidth of the memory component.

In deferred-activation mode 121, a “nominal” activation command 123directed to a given bank ‘B’ and storage row ‘Ra’ is received at t0(i.e., clock cycle 0), but instead of responsively executing a rowactivation operation, row activation is deferred until receipt of acolumn read/write command an arbitrary amount of time (t_(RCD-X)) later.More specifically, in the example shown, a column read command isreceived one clock cycle after the nominal activation command (i.e.,activation deferral interval or pre-activation delay, t_(RCD-X) is asingle clock cycle, t_(CK), in the example shown), and column addressbits therein are applied, in combination with the row address ‘Ra’supplied in row command 123, to trigger activation of a fractionalportion of the row of data specified by the row address. That is, therow address pre-selects the row (or page) to be fractionally activated,and the most significant bits of the later-arriving column addressselect the particular fraction of the row to be activated. Thus, thecolumn command triggers activation of a subrow (also referred to hereinas a “subpage”) identified in part by the column address provided in thecolumn command, and in part by the row address provided in a precedingrow command.

Still referring to FIG. 1 , the subpage identified by the column and rowaddresses is activated over a subpage activation interval t_(RCD-Y), anda column read operation is executed with respect to all or a part of theactivated subpage over a t_(CAC) interval so that the total delaybetween receipt (or registration) of activation-triggering columncommand 125 and output of corresponding read data, Q(BCa0) 126, is shownas the combination of those two time intervals. Comparing thedeferred-activation and immediate-activation modes, the net latencybetween initial row-command receipt and data output is the same despitethe additional pre-activation delay (t_(RCD-X)) within thedeferred-activation pipeline. While this need not be the case (i.e., thenet transaction latency in deferred-activation mode may be longer orshorter than in immediate-activation mode), in one embodiment subpageactivation takes slightly less time than activation of a complete rowdue in part to reduced power supply noise (i.e., less current is drawnin the fractional activation, thus reducing switching noise) and, asexplained further below, due to pre-selection of a global word lineprior to receipt of activation-triggering column command 125. In anycase, as in immediate-activation mode, a second column read command (RDBCb0, 127), received a t_(CC) interval after column read command 125,triggers output of a second column of read data, Q(BCb0) 128 back toback (i.e., without intervening time delay) with respect to the firstcolumn of read data. As discussed below, the second column command 127may trigger another subpage activation, activating a second fraction ofthe row specified by row command 123, or may access a column of datawithin the subpage specified by initial column read command 125.Accordingly, within a deferred-activation memory system, column commandsmay be distinguished as “activating” or non-activating, depending uponwhether their column addresses specify an unopened or open subpage,respectively. Further, as discussed below, differences in operationaltiming that apply between activating and non-activating column commandsmay be exploited by a controller component designed with awareness ofthe subpage architecture (e.g., subpage size) of the memory component.For example, such a “subpage-aware” controller component may commandprecharge operations at an earlier time following a non-activatingcolumn command than an activating column command on the understandingthat no row restore operation is required by the non-activating columncommand. A subpage-aware controller may also explicitly differentiatenon-activating and activating column commands in a given commandsequence (e.g., sending one type of command code to indicate anactivating column command, and another type of command code to indicatea non-activating column command) to exploit the reduced column latencypossible in the non-activating scenario.

Reflecting on the deferred-activation mode command sequences andconsidering in particular that “row activation command” 123 does not infact trigger an activation operation (i.e., data within core storagecells are not sensed in response to receipt of row command 123), itfollows that an alternative command nomenclature that more clearlyreflects the actions triggered by individual deferred-activation modecommands may avoid confusion. More specifically, because row command 123in actuality serves to load (or register) a row address within therecipient memory component rather than trigger a row activationoperation, such row-address bearing commands are referred to inembodiments that follow as “load” commands or “row-load” commands.Similarly, because column read and column write commands may triggersubpage (or subrow) activation operations, such column-address bearingcommands are referred to herein as activate-read and activate-writecommands. FIG. 2A illustrates an exemplary transition from thedeferred-activation command nomenclature of FIG. 1 to the row-load (L)and activate-read/write (AR) command nomenclature. Note that the bankaddress ‘B’, while present in all commands directed to a given storagebank, is implicitly rather than explicitly indicated in the revisednomenclature, with commands directed to a given storage bank indicatedby like-shading (or lack thereof). Thus, load command 143 (directed torow ‘Rx’) and activate-read commands 145 and 147 (directed to columns‘Ca0’ and ‘Cb0’, respectively) are directed to the same storage bank,while load command 143 (row address not specifically shown andcorresponding to command 133 in FIG. 1 ) is directed to a differentstorage bank. Also, in FIG. 2A and various command listings andtransaction diagrams that follow, column read commands (e.g.,activate-read “AR”) are depicted instead of column write commands. Anysuch commands may alternatively be column write commands (e.g.,activate-write commands) with column-access timing intervals (t_(CAC))being replaced by column-write delay intervals (t_(CWD)).

FIG. 2B presents a table of exemplary deferred-activation commands,including row commands, “load” and “precharge,” and column commands“activate-read” and “activate-read-precharge.” As shown, each of the rowcommands includes operation code (OP), device-address (Device), bankaddress (Bank) and row address (Row) fields that identify, respectively,the operation to be performed (e.g., load or precharge in the listingshown), the memory component to which the command is directed, one ofmultiple storage banks within the memory component and, at least in thecase of a load command, the row of storage cells of interest. Thedevice-address field may convey an encoded device ID value (e.g., to becompared with a preloaded or otherwise predetermined memory component IDand thus enable selection of one of multiple memory components to whichthe row command is transmitted) or a fully-decoded set of chip-selectsignals transmitted via chip-select lines to respective memorycomponents. In the latter arrangement a memory controller component mayraise one of the chip-select lines (i.e., one-hot configuration ofchip-select signals) to select, as the target device, one of multiplememory components coupled to the command/address path by which the rowcommand is transmitted.

As shown, the row address may be omitted from the precharge command (andthe command thus viewed as a “bank” command instead of a row command) asthat command triggers a bank precharge operation (decoupling apreviously activated set of storage cells from bit lines of the memorycomponent and arming the corresponding sense amplifiers for a subsequentactivation operation) that may be performed without identifying the rowcorresponding to the previously activated storage cells. By contrast, arow address is supplied with (i.e., as part of or in association with)each load command and loaded into a row address storage element (e.g.,register or latch) in response to command receipt. A row-address decodeoperation may also be executed in response to the load command to selectand assert a “global” word line that extends across multiple subpages ofthe address-specified bank. As explained in further detail below,asserting the global word line (i.e., asserting a control signal on theglobal word line) does not itself trigger an activation operation, andinstead serves to “preselect” the row of storage cells in which sub-pageactivation will eventually occur. Accordingly, the row-address load anddecode operation is also referred to herein as a “preselect operation,”as the global word line and thus the corresponding row of storage cellswithin the address-specified storage bank are preselected in preparationfor eventual subpage activation. In each of the embodiments disclosedherein, the row address decode operation indicated by a load command maybe commenced prior to receipt of corresponding column commands, therebyhiding the row-address decode time under the delay between row andcolumn command receipt.

Still referring to the command listing shown in FIG. 2B, each of thecolumn commands includes an operation code (OP), device address(Device), bank address (Bank) and column address (Column). In oneembodiment, the operation code includes an event field (also referred toherein as an event specifier) that indicates the actions to be carriedout in response to the command (e.g., activate, read/write, precharge,etc.), a read/write bit (R/W) that indicates whether the columnoperation is a read or write operation, and an optional burst-lengthfield (BL) that indicates the length of the outgoing read data sequenceor the incoming write data sequence and thus the quantum of read data tobe output or write data to be stored in response to the column command.

Still referring to FIG. 2B, when an activate-read command is receivedfollowing a load command, a subpage indicated by the column address isactivated over subpage-activation interval t_(RCD-Y) (i.e., as shown inthe deferred-activation transaction of FIG. 1 ), an operation in whichconstituent data bits of the specified subpage are transferred via bitlines to respective sense amplifiers and latched therein, therebyrendering the subpage “open” and available for column access. Followingsubpage activation, a column of read data specified by the columnaddress is transferred from the open subpage (i.e., within the senseamplifier set) to a data input/output (I/O) interface over column-readaccess interval, t_(CAC), and then output from the memory component overcolumn-to-column interval, t_(CC). After read data output, theactivate-read operation is deemed complete, though the subpage remainsopen within the sense amplifiers. A similar sequence of actions iscarried out in response to an activate-write command, except that writedata is received within the memory component over a t_(CC) interval and,when subpage activation is complete, transferred to an address-specifiedcolumn of sense amplifiers (within the activated subpage) over acolumn-write access interval, t_(CWD).

An activate-read-precharge command triggers the same actions as anactivate-read command and additionally triggers an automatic prechargeoperation (“auto-precharge”) a predetermined time, t_(RDP), aftercompleting subpage activation, with the tRDP interval spanning the timerequired to complete read access to the sense amplifiers containing theopen subpage so that the open subpage may be closed and the senseamplifiers re-armed for a subsequent activation operation. Similarly, anactivate-write-precharge command triggers the same actions as anactivate-write command and additionally triggers an auto-prechargeoperation a predetermined time, t_(WRP), after completing subpageactivation, with the t_(WRP) interval spanning the time required tocomplete write access to the sense amplifiers containing the opensubpage. In general, the auto-precharge operation triggered by anactivate-read-precharge or activate-write-precharge command isfunctionally equivalent to an auto-precharge operation in theimmediate-activation mode shown in FIG. 1 , but with different internaltiming to account for the subpage activation delay.

In a number of embodiments described herein, the column of data accessedin response to an activate-read or activate-write command is smallerthan the activated subpage. In the embodiment corresponding to thecommand table of FIG. 2B, for example, the most significant bits of thecolumn address are applied as a subpage address (SP) to select thesubpage (i.e., one of multiple subpages spanned by the row indicated bya preceding row-load command) to be activated, while the complete (andmore resolute) column address is supplied to column decoder circuitry toselect one of multiple columns of data encompassed by the activatedsubpage. By this arrangement, one or more additional column operations(read or write) may be issued following a subpage-activating columncommand to effect low-latency read/write operations with respect to theopen (activated) subpage. In alternative embodiments, the activatedsubpage may exactly match the quantum of data to be read or written inthe column operation, with the subpage address field and complete columnaddress being one and the same.

In at least one memory component embodiment, described below inreference to FIGS. 6A-6C, memory core control signals asserted inresponse to a subpage-activating column command are identical to thoseasserted in response to a non-activating column command (i.e., a columncommand directed to a previously activated subpage). That is, accesscontrol circuitry within the memory component latches the same subpageactivation control signals in response to both an initial activatingcolumn command and an ensuing “non-activating” command, with thelatching operation in response the non-activating command having a nulleffect with respect to control signal state (i.e., re-latching the sameset of control values so that no control signal transition and thus nointerference with the previously-triggered subpage activation occurs).One consequence of this design is that activating and non-activatingcolumn commands need not be distinguished within the command protocol.That is, the same activate-read or activate-write command type may beused to trigger a subpage-activating access and a non-activating access,depending on whether the specified subpage has been opened (or is in theprocess of being opened) in response to a preceding column command.Despite the simplified protocol and operational efficiency of thisarrangement, activating and non-activating column commands may bedifferentiated in alternative embodiments to obtain other benefits. Inan embodiment discussed below, for example, activating andnon-activating commands are differentiated (e.g., encoded with differentoperation codes) to take advantage of the lower latency of an access toan open subpage.

In general, the row and column commands shown in FIG. 2B are issued incombinations according to a subpage access policy implemented by amemory controller component. In one such access policy, referred toherein as an “open-page” policy, an activated subpage is left openindefinitely to enable a variable number of column operations followingan initial row-load command. More specifically, after a controllercomponent operating under an open-page policy opens one or more subpageswithin a given row and bank, the controller component will not issue aprecharge command until it receives a transaction request directed todifferent row within that bank. FIG. 3 illustrates the general format ofan exemplary open-page command sequence, starting with a prechargecommand (P) to close all open subpages within a previously specifiedrow, followed by a row-load command (L), and then concluding with atleast one and optionally multiple activate-read commands (AR) and/oractivate-write commands (i.e., an indefinite number of column commands).By contrast, in a “closed-page” access policy, one or more activatedsubpages corresponding to a given storage row are auto-prechargedfollowing a predetermined (though not necessarily fixed) number ofcolumn operations. FIG. 3 also illustrates the general format of anexemplary closed-page command sequence, beginning with a row-loadcommand (L), followed by an optional number (including zero) ofactivate-read commands (AR) and/or activate-write commands, andconcluding with an activate-read-precharge command (i.e., activate-read,followed by an auto-precharge) or activate-write-precharge command.Thus, under an open-page policy, each transaction sequence directed to agiven storage row and bank begins with a precharge to close the row leftopen indefinitely during the preceding transaction sequence directed tothat bank, while under a closed-page policy each transaction sequenceconcludes with a precharge operation, generally after a deterministicnumber of column operations or lapse of a predetermined amount of time.In both the open and closed-page command sequences, the optionalactivate-read commands may trigger a sub-page activation or, if precededby an activate-read directed to the same subpage, may access data withina previously activated-subpage and thus constitute non-activating columncommands.

FIG. 4A illustrates an exemplary open-page, deferred-activation memoryprotocol within a synchronous memory system. In general, row and columncommands are transmitted from a controller component to a memorycomponent via a command transmission path (i.e., formed by one or morecommand/address (CA) signaling links) during respective cycles of aclock signal, CK, and read and write data is conveyed between thecontroller and memory components via a bidirectional data signalingpath, DQ. For ease of understanding, the command transmission path,depicted in FIG. 4A and other figures that follow as “CA-ALL,” is splitinto three logical transmission paths according to commands conveyed.More specifically, row-load commands, activate-read commands andprecharge commands are depicted as being transmitted on separate logicalpaths, CA-ROW, CA-COL and CA-PRE, respectively, to emphasize commandtiming and relationships, but in actuality are transmitted via unifiedcommand path, CA-ALL. Also, all commands shown are assumed to bedirected to a single, multi-bank memory component, with the bankaddressed in a given command implied by shading of the command (or lackthereof). Thus, within the core-specific minimum time between activationoperations within the same bank, t_(RC), row load commands (L) to fivedifferent banks are issued at clock cycles 0, 4, 8, 12 and 16,respectively. To avoid undue complexity, address values are omitted fromshaded row and column commands (and marked in unshaded row and columncommands only) but should be understood to be present nonetheless. Withregard to address notation, row addresses are denoted in FIG. 4A andother protocol diagrams that follow by ‘R<row address>’ and columnaddresses are denoted by ‘C<subpage address><offset>. For example, ‘Rx’and ‘Ry’ denote row addresses corresponding to rows ‘x’ and ‘y’ of agiven bank, and ‘Ca0’ and ‘Ca1’ denote column addresses corresponding tocolumns of data at different offsets within subpage ‘a’ of a given row(by contrast, ‘Ca0’ and ‘Cb0’ denote column address corresponding tocolumns of data within different subpages). Finally, core operationsdirected to a given subpage are identified by reference to the rowaddress and subpage address of the subpage. Thus, a sensing operationwith respect to subpage ‘a’ of row ‘x’ is identified as operation ‘xa.’

Continuing with FIG. 4A, a single-clock-cycle deferral interval (i.e.,t_(RCD-X)=t_(CK)) transpires between receipt of a row-load command 143directed to row ‘Rx’ within a given bank (i.e., L Rx), and receipt of anactivate-read command 145 directed to column ‘Ca0’ of that same bank(i.e., AR Ca0). As explained, in the deferred-activation mode shown, rowactivation is not initiated in response to row-load command 143, andinstead is deferred until receipt of column command 145 at least oneclock cycle later. The column address (Ca0) provided in the columncommand and row address (Rx) provided in the row-load command arejointly applied to select a subpage within the specified storage bank,with activation of the subpage being triggered by receipt of the columncommand. This result is reflected in the memory core activity sequenceshown at the bottom of the protocol diagram, in which global word linepre-selection 180 (Pre-sel GWL) is initiated in response to row-loadcommand 143, and a subpage activation operation 182 (“Sensing Subpagexa”) begins one clock cycle later in response to activate-read command145.

In the particular embodiment shown, subpage activation is assumed torequire an interval corresponding to five clock cycles (t_(CK)*5, thougha longer or shorter interval may apply depending on the memory coretechnology and/or architecture), and is followed by a restorationoperation 184 (i.e., driving the data latched within the senseamplifiers back into the storage cells in preparation for an eventualprecharge operation 187 as shown in the core activity timeline) thattranspires over the ensuing six clock cycles. One to two clock cyclesafter the subpage activation (sensing) operation is completed, andconcurrently with the restoration of the subpage, a column accessdirected to the open page is carried out over a t_(CAC) interval, with acolumn-address-specified column of data being retrieved from the openpage (i.e., from the sense amplifiers holding the activated subpage) androuted to a serializing output driver. Thus, the memory componentresponds to activate-read command 145 by outputting theaddress-specified column of read data Q(Ca0) 146 after a totalcolumn-latency interval (CL) that includes subpage-activation interval,t_(RCD-Y), and column access interval, t_(CAC). In the embodiment shown,read data Q(Ca0) 146 is output over a t_(CC) interval as a sequence oftransmit values, where each transmit value includes a number of bitsequal to the width of the data signaling interface (W), and the numberof transmit intervals or “burst length” is equal to the quantum ofcolumn data (the column size) divided by W. In a column write operation(i.e., activate-write command received instead of activate-read command145), subpage activation is executed as described above, with write databeing received over a t_(CC) interval starting at a time delayedrelative to completion of the subpage activation operation by intervalt_(CWD). In a subpage activation triggered by a column write, thesubpage sensing time may be shortened relative to that of a column readdue to the data flow direction. That is, the subpage data need not befully latched in the sense amplifiers before write data is applied asthe subpage data will be overwritten anyway.

Still referring to FIG. 4A, activate-read command 145 is followed at_(CC) interval later by another activate-read command 147 directed tothe same bank and thus to the row of storage cells specified by rowcommand 143. For purposes of example, the second activate-read command147 is assumed to specify an unopened subpage (i.e., the columnaddresses Ca0 and Cb0 of the two commands 145, 147 correspond to data indifferent subpages) and thus triggers a second subpage activation. Thisevent is reflected in the core activity timeline which shows sensing(activation) and restoring operations (183, 185) with respect to asecond subpage (“Subpage xb”) over respective intervals that arestaggered by a t_(CC) interval relative to sense/restoration operations(182, 184) for the first subpage. As in the initial activate-readoperation, read data 148 is output with a net column latencyt_(RCD-Y)+t_(CAC) relative to receipt of activate-read command 147, andthus back-to-back with respect to the read data output in response toactivate-read command 145.

Because the subpage activation operations triggered by activate-readcommands 145 and 147 are directed to the same storage bank, a singleprecharge operation may be performed to close all open subpages withinthe bank and prepare the bank for subsequent pre-selection and subpageactivation operations. As shown in the core activity timeline, such aprecharge operation (187) is not begun until subpage restoration iscompleted with respect to the last-received activate-read command; inthis case, activate-read command 147. As discussed below, this timingconstraint has implications for the memory control protocol, as thefinal activate-read command in a given transaction sequence may resolveto a subpage opened in response to a previous activate-read command inthe same sequence, thus shortening the overall core activity timelineand enabling precharge at an earlier time than shown in FIG. 4A. Suchshort-interval command sequences are discussed below in reference tosubpage-aware memory protocols.

Continuing with the exemplary multi-activate command sequence shown inFIG. 4A (i.e., multiple subpage activations are carried out with respectto row-load command 143), a precharge command 149 is received after adelay that corresponds to the sub-page activation interval, t_(RCD-Y),plus a subpage restoration interval, t_(RDP), and thus at the conclusionof the second subpage restoration 185 for the command sequence shown.The precharge operation itself takes place over a time interval t_(RP),after which a new row-load command 163 directed to the precharged bankmay be executed. In the case of an activate-write command sequence, theprecharge command is received after a delay t_(RCD-Y) (subpageactivation interval) plus t_(WRP) (restoration time following writeoperation within the activated subpage).

As FIG. 4A illustrates, command sequences directed to five differentbanks in round-robin fashion are sufficient to fully consume theavailable transmission intervals on the command/address path (CA-ALL)and data path (DQ). Thus, while the memory access latency with respectto any single deferred-activation command sequence (e.g., time betweenarrival of row-load command and read data output) may potentially beincreased by as much as t_(RCD-X) relative to an immediate-activationcommand sequence (i.e., activation triggered upon receipt ofrow-address-bearing command), peak memory bandwidth remains unchangedand constrained only by the data signaling rate.

FIG. 4B illustrates an exemplary closed-page deferred-activationprotocol in which a command sequence directed to a given row and bank isconcluded by an activate-read-precharge command. That is, instead of asequence of activate-read commands followed by an explicit prechargecommand as in FIG. 4A, an initial activate-read command 145 is followedby an activate-read-precharge command 205 (ARP Cb0). As explained above,the activate-read-precharge command initiates the same core actions asan activate-read command, and additionally schedules an automaticprecharge at the conclusion of the subpage activation/restorationoperation. This is illustrated diagrammatically by “notional” prechargecommand 206 (i.e., a command shown in dashed outline to indicate that itis not actually issued, but rather presented to illustrate the timing ofoperations scheduled or triggered in response to another command) whichshows the timing of the precharge operation executed in response toactivate-read-precharge command 205, an “auto-precharging” activate-readcommand. Accordingly, the same sequence of actions (global word linepre-selection, followed by two subpage activations and correspondingcolumn accesses) is effectuated by the command sequences of FIGS. 4A and4B, but the CA bandwidth consumption is reduced in the latter as noexplicit precharge command is transmitted. The freed command/addressbandwidth may be re-applied, for example, to enable conveyance ofmaintenance or configuration commands (e.g., refresh commands, timingcalibration commands, signaling calibration commands, registerprogramming commands etc.) without having to interrupt the memory accesscommand stream.

FIG. 5A illustrates an embodiment of a memory bank 250 that may beemployed within a multi-bank memory component to enable thedeferred-activation operations discussed above. As shown, the memorybank includes row and column decoders 251 and 253, subpagedecode/activate logic 255, and bank storage array 260. The bank storagearray itself includes a number of subarrays 259 arranged in rows andcolumns and bordered by sense amplifier (SA) stripes 261 andsub-word-line (SWL) select stripes 263. Each sense amplifier stripe andsub-word select stripe is formed by respective segments, referred toherein as sense-amp segments 262 and SWL-select segments 264, withsubpage activate logic 265 provided at the corner between each SAsegment and SWL-select segment.

When a row-load command directed to memory bank 250 is received withinthe host memory component (i.e., the memory component containing memorybank 250), a command decoder (not shown in FIG. 5A) forwards the rowaddress within (or associated with) the command to row decoder 251 andoutputs a row-address strobe (RAS) signal to row decoder 251. Rowdecoder 251 responds to the RAS signal by latching the row address(e.g., within an address register or latch) and decoding the latched rowaddress to pre-select a global word line 267. More specifically, the rowdecoder 251 asserts (e.g., driving the global word line to an active-lowstate) a row-address-specified one of a plurality of global word lines267 that extend across memory bank 250, and also asserts a pair ofsense-amp stripe enable signals 269 corresponding to the pair of senseamplifier stripes that bound the row of subarrays spanned by theasserted global word line. This pre-selection operation is shown in FIG.5A by the dashed global word line 267 (i.e., the global word lineasserted following the row-address decode) and dashed pair of sense-ampstripe enable signals 269.

FIG. 5B illustrates a progressed state of memory bank 250 that followsreceipt of an activate-read command within the host memory component.The most significant bits of a column address provided within or inassociation with the activate-read command are provided to subpagedecode/activate logic 255 which, in turn, decodes the column addressbits to trigger a latching operation within one of subpage stripelatches 257. In the particular example shown, the column address (orMSBs thereof) resolves to the second of eight subarray columns withinmemory bank 250 so that the subpage decode/activate logic 255 assertscontrol signals 258 to trigger a latching operation within the subpagestripe latch 275 for that column of subarrays. In one embodiment, thetriggered subpage stripe latch 275 successively raises a sub-word-line(SWL) enable signal and a sense amp (SA) enable signal (showncollectively at 277) which are logically combined (e.g., logicallyANDed) with the preselected global word line and sense-amp stripe enablesignals, respectively, to enable access to a subrow of storage cellswithin subarray 278—the subarray at the intersection of the pre-selectedglobal word line and the asserted SWL enable signals. More specifically,the SWL enable signal is logically combined with the preselected globalword line within SWL-select segment 279 to raise (or lower or otherwiseassert or energize) sub-word line 284 within the subarray specified bythe combined row and column addresses, and the SA enable signal (raisedshortly after the SWL enable signal) is logically combined with thepreselected SA stripe enable signals to enable SA segments 281 a and 281b to sense and latch data output from the storage cells coupled toasserted sub-word line 284. That is, in the embodiment shown, the SAsegments 281 a, 281 b on either side of the target subarray 278 arecoupled alternately to even numbered and odd numbered bit lines of thesubarray and thus, even numbered data bits (0, 2, 4, 6 . . . ) arelatched in one of the SA segments (e.g., 281 a) and odd numbered databits are latched in the other SA segment (e.g., 281 b). Together, theeven and odd data within the SA stripe segments constitute an opensubpage (or open subrow). All other SA segments on the same stripes asSA segments 281 a, 281 b remain, throughout this operation, in anequalized bit line or precharged state.

FIG. 5C illustrates a further progression in the state of memory bank250 as a selected portion of the subpage data is conveyed to columndecoder 253 via selected core I/O lines 283. More specifically, columndecoder 253 responds to assertion of the column-address-strobe (CAS)signal (or a signal derived therefrom) by establishing a multiplexedpath between a column of core I/O lines specified by the column address(i.e., core I/O lines 283) and the data I/O interface of the memorycomponent. Thus, after the address-specified subpage of data is capturedwithin sense amplifier segments 281 a, 281 b, a column of data is routedvia column-address-specified core I/O lines 283 from the open subpage tothe data I/O interface where it is serialized and transmitted as readdata over the DQ signaling links. The reverse operation occurs inresponse to an activate-write command, with write data being receivedwithin the data I/O interface via the DQ signaling links, deserializedto form a column of write data and conveyed to the open subpage via coreI/O lines 283 to overwrite (replace) the corresponding column of datatherein. As explained above, during at least part of the column dataaccess via the core I/O lines (i.e., during a t_(CAC) interval in acolumn read operation and during a t_(CWD) interval in a column writeoperation), the contents of the open subpage are driven back to theaccessed subrow of memory cells to restore the data values therein. Thatis, because the subpage activation tends to be destructive (e.g., in thecase of a DRAM, the small charges stored within capacitive storage cellstend to be dissipated when transferred to the bit lines to enable thecell states to be sensed), the latched values within the sense amplifiersegments 281 a, 281 b are regeneratively applied to recharge the bitlines coupled to subarray 278 and thereby restore the charge states ofthe originally sensed storage cells. This operation is depicted as“Restoring Subpage xa” (184) in the protocol diagram of FIG. 4A.

In the embodiment of FIGS. 5A-5D, the column of data accessed inresponse to a given column command is assumed to be narrower than theopen subpage (i.e., the MSBs of the column address are applied tosubpage decode/activate logic 255, and the full column address isapplied to column decoder 253) so that each column access reads orwrites only a fraction of the open subpage. Although the widths of thesubarrays 259 and accessed data columns may be matched in alternativeembodiments (in which case the full column address is supplied to bothsubpage decode/activate logic 255 and to column decoder 253), themulti-column per subarray arrangement shown may be used to exploit datalocality and temporality principles by directing multiple columnoperations to the same open subpage. Also, while the most-significantbits of the column address are applied to specify the subpage to beactivated in the embodiment of FIGS. 5A-5D and other embodiments herein,in all such cases other groups or combinations of bits within the columnaddress may be used to specify the subpage to be activated.

In FIG. 5C, a second subpage activation operation is carried outconcurrently with retrieval of the read data column from the initiallyopen subpage. More specifically, a second activate-read command isreceived within the host memory component a t_(CC) interval after thefirst, and the column address therein (or associated therewith) isapplied to subpage decode/activate logic 255 to trigger a latchingoperation within another of the subpage stripe latches 257. In theexample shown, the column address (or MSBs thereof) resolves to thesixth of eight subarray columns, with the corresponding subpage stripelatch 285 raising SWL enable and SA enable signals (shown collectivelyat 287) to enable access to a row of storage cells within the subarray(288) at the intersection of the asserted global word line and SWLenable signals. That is, the SWL enable signal is logically combinedwith the pre-selected global word line within SWL-select segment 289 toraise (or energize) sub-word line 294 within the subarray specified bythe combined row and column addresses, and the SA enable signal (raisedshortly after the SWL enable signal) is logically combined with thepre-selected SA stripe enable signals to enable SA stripe segments 291 aand 291 b to sense and latch data output from the storage cells coupledto asserted sub-word line 294.

Approximately one t_(CC) interval after the column access is initiatedwith respect to subarray 278 (i.e., the time between successiveactivate-read commands that triggered the subpage activations withinsubarrays 278 and 288), multiplexing logic within column decoder 253 isswitched to enable column access to subpage data from subarray 288. Thisevent is illustrated in FIG. 5D by the depiction of acolumn-address-specified set of core I/O lines 293 through which readdata is retrieved from the newly opened page. At this point one or moreadditional non-activating column operations may be directed to either ofthe open subpages, or one or more additional activating columnoperations may be executed, repeating the sequence of actions describedin reference to subarrays 278 and 288. Alternatively, the bank may beprecharged in response to an explicit precharge command or anactivate-read-precharge command, resetting the subpage stripe latches257 (thereby lowering all SWL enable signals and SA enable signalsasserted by selected subpage stripe latches 275 and 285) and deassertingthe global word line and stripe enable signal and thus preparing bank250 for a subsequent access to a different row of storage cells. Becausethe other subarrays horizontally adjacent to subarrays 278 and 288 werenever disturbed from a precharged state, the precharge command does notaffect them, and precharge power consumption is reduced as compared to aconventional row-wide precharge operation.

FIG. 6A illustrates a more detailed view of exemplary circuit blocksthat may be used to implement the memory bank 250 of FIGS. 5A-5C. Morespecifically, a four-subarray corner portion of a larger bank isdepicted, with each subarray designated according to its coordinateswithin a grid of SWL-select stripes and SA stripes: subarray 0,0;subarray 0,1; subarray 1,0; and subarray 1,1. Two sense amp stripes (0and 1) and two sub-word line stripes (0 and 1) are also shown, with eachdecomposed into a pair of sense amp segments 329 denominated by stripenumber and segment number. Subpage activate circuits 321, each includingconstituent SWL enable and SA enable circuits 323 a and 323 b, aredisposed at respective corners formed by the SA segments 329 andSWL-select segments 328. Each column of subpage activate circuits iscoupled to receive control signals from a respective subpage stripelatch 315-0, 315-1, which is in turn controlled by subpagedecode/activate logic 305. Though not specifically shown, column decoder303 is coupled to the SA stripe segments via core I/O lines that extendparallel to the SWL select stripes across the grid of subarrays.Similarly, row decoder 301 is coupled to the SWL select stripes viaglobal word lines (not specifically shown) that extend across thesubarrays parallel to the SA stripes. The row decoder is also coupled tothe SA stripes via SA stripe enable signals (two of which are shown)which extend parallel to the SA stripes and are each coupled torespective sets of subpage activate circuits 321 disposed in line with agiven SA stripe.

When a row-load command is received, the associated row address isstrobed into the row decoder and decoded therein to assert anaddress-specified global word line and corresponding pair of sense-ampstripe enable signals (i.e., the sense-amp stripe enable signalscorresponding to the stripes that bound the row of subarrays spanned bythe address-specified global word line). One or more clock cycles later,when a column command is received (e.g., activate-read oractivate-write), the most significant ‘m’ bits of the column address arestrobed into subpage decode/activate logic 305, while the full ‘n’ bitsof the column address are supplied to column decoder 303. Morespecifically, the full column address is supplied to column accesspipeline logic 311 to control multiplexing operations within columndecode logic 312.

Subpage decode/activate logic 305 decodes the incoming ‘m’ mostsignificant bits of the column address (also referred to herein as asubrow address or subpage address) to generate a an N-bit select value(i.e., “Sel[N−1:0],” where N=2^(m)) having a set bit in a position thatcorresponds to the column index of the subarray to be accessed. Forexample, in a storage bank having an 8×8 matrix of subarrays in whichthe subarray in row 0, column 1 (i.e., subarray 0,1) is to be accessed,a three bit subpage address corresponding to an initial activate-readcommand is decoded to generate an eight-bit select value having asolitary set bit in position 1 (i.e., ‘00000010’). Thereafter, andcontinuing until a precharge operation is initiated, the subpage addressprovided with each additional column command is logically OR'd with thepreviously generated select value to generate the updated select value.Thus, if the subpage address corresponding to a second activate-readcommand specifies the fifth column of subarrays (e.g., subarray 0,5),the subpage decode/activate logic yields an updated select value havingset bits in positions 1 and 5 (i.e., ‘00100010’). As shown, individualselect bits of the select value (“Sel0,” “Sel1,” etc.) are supplied torespective subpage stripe latches (315-0, 3150-1, etc.) so that, whensubpage decode/activate logic 305 asserts a sub-word line strobe signal(“SWL Strobe”), the select bits are loaded into respective SWL latchcircuits (316-0, 316-1, etc.) and output therefrom in the form ofcorresponding SWL-enable and SA enable signals for the correspondingcolumn of subarrays. By this arrangement, the subpage address portion ofeach incoming column address enables assertion of a respective SWLenable signal, with each new subpage-activating column command enablingassertion of an additional SWL enable signal. In one embodiment, subpagedecode/activate logic 305 additionally asserts a sense-amp strobe signal(“SA Strobe”) in response to each new subpage address a short time afterasserting the SWL strobe, thereby loading the select bits intorespective SA latch circuits (317-0, 317-1, etc.) and thus generatingsense amp enable signals corresponding to the address-specified columnor columns of subarrays.

Still referring to FIG. 6A, subpage decode/activate logic 305 respondsto assertion of a precharge signal, “Pre” (i.e., signaling a prechargeoperation), by resetting the select value to a non-selecting state(i.e., ‘00000000’) and asserting a reset signal to clear the contents ofthe constituent SWL and SA latch elements (collectively, 316, 317) ofeach subpage stripe latch. By this action, the SWL enable and SA enablesignals are deasserted for all columns of subarrays, thereby enablingsubpage decode/activate logic 305 to re-arm the SWL select stripesegments and SA stripe segments for access within a different row. In analternative embodiment, the reset signal may be omitted, and the SWL andSA strobe signals asserted instead by subpage decode/activate logic 305to load the non-selecting select value into the constituent latchelements 316, 317 of subpage stripe latches 315, thereby resetting thesubpage stripe latches 315 and deasserting the corresponding SWL and SAenable signals.

In one embodiment, each of the constituent SWL and SA latch elements316, 317 within subpage stripe latches 315 is implemented by atransparent latch that enables the incoming select bit to flow throughto the latch output (i.e., as a SWL enable signal or SA enable signal)when the corresponding strobe signal is asserted, and then latches theoutput state when the strobe signal is deasserted. By this design, theSWL enable and SA enable signals asserted by a given pair of latchesremain asserted when those latches are reloaded with same-state selectbits, meaning that the subpage decode/activate logic 305 may execute aconsistent sequence of actions (updating the select value, thensuccessively strobing the SWL and SA strobe signals) in response to eachincoming activate-read or activate-write command, regardless of whethersubpage activation has been previously initiated within the targetsubarray. Thus, if the subpage address associated with a givenactivate-read command results in assertion of SWL enable signal and SAenable signal for subarrays x,0 (e.g., loading a logic ‘1’ bit into SWLlatch element 316-0 and SA latch element 317-0), a subsequentactivate-read command bearing the same subpage address yields the sameactions within the subpage decode/activate logic as the first, in effectyielding the same select value (including additional set bits resultingfrom intervening activate-read or activate-write commands bearingdifferent subpage addresses, if any) and glitchlessly latching the sameset bits within SWL and SA latch elements 316-0, 317-0. Said anotherway, the subpage decode/activate logic executes the same sequence ofoperations regardless of whether an incoming column command triggers asubpage activation (new subpage address and thus responsive assertion ofSWL and SA enable signal) or not (i.e., repeated subpage address andthus no change in state of previously asserted SWL and SA enablesignals). From a command protocol standpoint, this means that nodistinction need be made between activating and non-activating columncommands, and thus that a single command type may be used to triggerboth types of column access operations. Conversely, because the subpageactivation delay is at least partly consumed by the interval between twocolumn commands directed to the same subpage, the net column accesslatency for the latter of the column commands may optionally be reduced,yielding a reduced column latency (CL) relative to an activating columncommand. Further, if the last of multiple column commands correspondingto a given row-load command is a non-activating read command (i.e.,bears a subpage address matching that provided in another of the columncommands), no subpage restoration is required in connection with thelast column command (as no subpage activation was triggered by thecommand) so that bank precharge may be initiated at an earlier point intime (i.e., advanced), thereby reducing the row-to-row latency (t_(RC))with respect to the subject storage bank. Either or both of theselatency reductions (CL and t_(RC)) may be exploited within a memorysystem having a subpage-aware controller component—a controllercomponent designed and operated with awareness of the subpage activationarchitecture within an attached memory component and thus capable ofdetermining, based upon the column addresses provided in connection witha sequence of column access commands whether a given one of the columncommands will trigger a subpage activation or not (i.e., is anactivating or non-activating command). Examples of such subpage-awareoperation are discussed in embodiments below, including an embodiment inwhich the precharge time is advanced upon determining a given commandsequence is concluded by a non-activating column read command, and anembodiment in which activating and non-activating column read commandsare differentiated within the command protocol to permit opportunisticcolumn latency reduction.

FIG. 6B illustrates embodiments of subpage activate circuits 343 andSWL-select circuits 351 (designated by the row and column of thesubarrays to which they correspond) that may be used to implement thesubpage activate logic 321 and SWL-select segments 328 shown in FIG. 6A.Each SWL-select circuit 351 includes a set of logic AND elements 353 todrive a respective sub word line in accordance with global word line andSWL enable signal inputs. As shown by dashed signal lines in FIG. 6B,global word line GWLn+1 is pre-selected (i.e., asserted in response to arow-load command bearing an address that decodes to that word line), andcorresponding stripe enable signals 322 for the row of subarrays spannedby the pre-selected global word line are asserted (note that, forsimplicity, only a single SA stripe is shown with respect to each row ofsubarrays). By this operation, the SWL select stripe segments and SAstripe segments corresponding to the row of subarrays spanned by theglobal word line are, in effect, armed in preparation for assertion ofSWL enable and SA enable signals corresponding to a column-addressspecified column of the subarrays.

FIG. 6C illustrates the state of the memory bank architecture of FIG. 6Bfollowing receipt of a column command. As shown at (2), the SWL enableand SA enable lines corresponding to a target column of subarrays areasserted in succession. The SWL enable signal and SA enable signal arelogically ANDed in gate 345 (part of subpage activate circuit 343) toraise a local SWL-select signal 346. The local SWL-select signal 346 andasserted global word line 342 have an intersecting destination at logicgate 353 (part of SWL-select circuit 351) where the signals arelogically ANDed to energize subpage word line (or sub-word line) 354.Similarly, the SA enable signal and asserted stripe enable signal arecombined within logic gate 347 to raise a SA segment-enable signal 348and thereby enable a sensing operation within sense amp segment 353 ashort while after subpage word line 354 is raised. By this operation,subpage data output from the subrow of storage cells controlled bysubpage word line 354 are enabled onto the bit lines of subarray 1,0 andthen sensed and latched within the sense amp segment 353. As explained,sense amp segments disposed at opposite sides of a given subarray may becoupled to even- and odd-numbered bit lines, respectively, andsimultaneously enabled by respective SA segment enable signals to senseand latch even and odd subpage data.

Still referring to FIG. 6C, the open subpage within sense amp segmentsbounding the target subarray (i.e., subarray 1,0 in this example) isaccessed via the core I/O lines (“Core I/O”) as discussed above. Morespecifically, in a column read operation, the column multiplexerswitchably forms a signal path between a column-address-specified subsetof the core I/O lines (i.e., a number of lines corresponding to theamount of data to be transferred) and a serializing output driver, andin a column write operation, the column multiplexer switchably forms asignal path between the column-address-specified subset of the core I/Olines and a deserializing receiver, in either case enabling datatransfer between the sense amplifiers containing the open subpage andthe data I/O interface of the memory component via a selected subset ofthe core I/O lines and local I/O lines 355 coupled to the enabled senseamp segments.

Reflecting on FIGS. 6A-6C, it should be noted that a number of changesmay be made to the circuitry shown to save area and speed up operation.For example, a number of the control signals may be interleaved anddriven alternately from the left or right side (or top or bottom) of agiven subarray and/or sense-amp segment. Also, the sense-amp enablesignal may be decoded outside of the array to generate elemental controlsignals corresponding to the sequence of actions to be performed as partof a sense or restore operation, with the elemental control signalsbeing delivered to the sense amplifiers to trigger those actions.

FIG. 7A illustrates a reduced-latency transaction protocol that may beimplemented by a controller component that is aware of (i.e., designedto assume or detect the presence of) the deferred activation,subpage-access memory component architecture described in reference toFIGS. 5A-5D and 6A-6C. That is, the controller component may evaluatecolumn addresses within a sequence of column commands to determine whena given column command is directed to a subpage that is already open orin the process of being opened (i.e., activated in response to a priorcolumn command). Upon detecting a column command directed to an opensubpage (including a subpage still in the process of being opened), thecontroller component may advance the timing of a subsequent prechargeoperation on the designed-in assumption that, because no subpageactivation was triggered by the command directed to the open subpage,the usual sequence of pipelined delays associated with subpageactivation ends with the restoration phase of the open subpage. That is,as shown by the core activity timeline in FIG. 7A, the receipt of twocolumn commands directed to the same subpage (i.e., one command 145directed to column ‘a0’ and the other command 375 directed to column‘a1’ within subpage ‘a’), no subpage activation and thus no subpagesensing or restoration operations are initiated in response to thelatter column command 375. Accordingly, a bank precharge operation maybe initiated at the conclusion of the core activity with respect to thesubpage activated in response to initial command 145 (i.e., afterrestoration of subpage xa as shown at 184) and thus a column cycle(t_(CC)) interval earlier (i.e., the offset between the successivesame-subpage column commands) than in the case where successive subpageactivations are triggered. This result is illustrated in FIG. 7A by theearly transmission of precharge command 149 (i.e., arriving clock edge12 instead of clock edge 14), and corresponding early execution andcompletion of the precharge operation shown at 187 within the coreactivity timeline. The net result is that the total transaction timewith respect to the row and thus the intra-bank row-to-row latency,t_(RC), is reduced by a t_(CC) interval.

In the embodiment of FIG. 7A, the controller component behavesopportunistically with respect to the outgoing command sequence,dynamically establishing one of two different t_(RC) latencies accordingto whether the last of the column commands triggers a subpage activationor is instead directed to a subpage opened in response to a prior columncommand in the command sequence (i.e., whether or not the last columncommand in the sequence is an activating or non-activating columncommand). In the former case, the timing shown in FIG. 4A applies, withthe subpage-sense and restore delay (t_(RCD-Y)+T_(RDP)) being appliedwith respect to the last-received column command, and in the lattercase, the timing shown in FIG. 7A applies, with the subpage-sense andrestore delay being applied with respect to a column command other thanthe last-received column command (i.e., whichever of the column commandsassociated with a given row-load command was the last to trigger asubpage activation).

In a memory component that supports the protocol example shown in FIG.7A, the early precharge operation triggered by command 149 closes theopen subpage (including, for example, restoring the subpage senseamplifiers to an un-latched state in preparation for a subsequentsubpage activation) shortly after data 376 is conveyed from the subpagesense amplifiers to logic within the data I/O interface and thus doesnot compromise the column read operation. In memory components thatexhibit relatively fast precharge timing, additional delay may beimposed in the precharge circuitry and/or in the command protocol toavoid a race between data retrieval and subpage closure.

FIG. 7B illustrates another exemplary subpage-aware transactionprotocol, in this case employing an auto-precharging activate-readcommand out of order with respect to a non-precharging activate-readcommand. That is, upon detecting that a pair of column access commands373 and 375 in a closed-page (auto-precharging) command sequence aredirected to the same subpage, the controller component may issue anauto-precharging activate-read command ahead of the non-prechargingactivate-read command, thereby reversing the command order relative tothat carried out in a closed-page command sequence in which theconstituent column commands are directed to different subpages and thuseach trigger a subpage activation. The net effect is a closed-pageaccess sequence in which precharge is begun earlier (i.e., at theconclusion of the subpage activation triggered by pre-chargingactivate-read command 353, and thus at a time corresponding to notionalpre-charge command 377) to yield a reduced intra-bank row-to-rowlatency, tRC. As shown at 374, 376, read data output in response to thetwo column commands is carried out with the column latency(t_(RCD-Y)+t_(CAC)) described above. Also, a second closed-page sequencewith reverse-order precharging and non-precharging commands (383, 385)and corresponding data output (384, 386) is shown with respect torow-load command 163.

Comparing the open-page and closed-page protocols shown in FIGS. 7A and7B, it can be seen that, while a dynamic, subpage-aware timing appliesin the open-page command sequence of FIG. 7A (i.e., as the prechargecommand and subsequent row-load command are issued at different timesrelative to column command transmission according to whether the last ofthe column commands is directed to an open (or opening) subpage), nochange occurs in the sequence of command types regardless of whether theconstituent column commands are directed to the same or differentsubpages. By contrast, in the closed-page protocol shown in FIG. 7B, thecontroller applies a dynamic, subpage-aware command order in addition tothe dynamic command timing, issuing an auto-precharging column commandahead of a non-precharging column command in a sequence of columncommands directed to the same subpage (i.e., at least the final columncommand being directed to a subpage activated in response to a priorcolumn command in the same sequence), and reversing that order when thefinal column command in the sequence is directed to an unopened subpageand thus triggers a subpage activation. With regard to dynamic timing,though the explicit precharge command is omitted in the closed-pagesequence, the shortened t_(RC) latency still applies in the dual subpageaccess sequence (i.e., the subpage address within the final columncommand is a duplicate or match of a subpage address within an earliercolumn command directed to same preselected row), so that the controllercomponent may dynamically shorten or increase the delay between row-loadcommands directed to the same bank according to the addresses thatappear within the corresponding column command sequences.

FIG. 8 illustrates an alternative set of exemplary deferred-activationcommands, including the row and column commands shown in FIG. 2B (i.e.,load, precharge, activate-read and precharge-activate-read), as well asa pair of non-activating column commands, “Read” and “Read-Precharge”,both of which alternatively may be write commands (“Write” and“Write-Precharge). The “Read” and “Read-Precharge” commands are referredto herein as explicit non-activation commands, as their non-activatingstatus is indicated explicitly by a differentiated command code ratherthan through mere repetition of the subpage address of a prior columncommand, as in the case of the implicit non-activation commandsdiscussed above. As explained below in reference to FIGS. 10A and 10B,explicit non-activation column commands may be used to effect read andwrite operations with reduced column latency relative to theiractivating counterparts, and are thus also referred to herein aslow-latency column commands. Thus, contrasting the activate-read commandand the low-latency read command presented within FIG. 8 , both includedevice, bank and column address fields, and both initiate a column readoperation, but as the difference in command name implies, no subpageactivation occurs in response to the low-latency read command, so thatthe t_(RCD-Y) interval otherwise imposed as part of the total columnlatency time does not apply. Thus, a t_(CAC) interval after arrival ofthe low-latency read command, read data is output from the memorycomponent. Similarly, a t_(CWD) interval after arriving of a low-latencywrite command, write data is received within the memory device forstorage within the open subpage.

FIG. 9 illustrates closed-page and open-page access sequences supportedby a memory system that explicitly differentiates between activating andnon-activating column commands (i.e., as in the command tabulation ofFIG. 8 ). Thus, in addition to the two command sequences presented inFIG. 3 and repeated in FIG. 9 , open-page command sequence 391 includesa precharge command to close all open subpages within a previouslyspecified row, followed by a row-load command (L), and then by at leastone activating read (or write) command (AR or AW), and then concludingwith at least one and possibly multiple low-latency read and/or writecommands (R or W). Similarly, an additional closed-page command sequence392 includes a row-load command (L) followed by at least one activatingread (or write) command (AR or AW), followed in turn by an optionalnumber of (including zero) low-latency read and/or write commands (R orW), and then concluding with a non-activating, auto-precharging readcommand or non-activating, auto-precharging write command (RP or WP).

FIGS. 10A and 10B illustrate examples of open-page and closed-pagememory protocols, respectively, corresponding to theactivation-differentiated column command sequences 391 and 392 shown inFIG. 9 . In FIG. 10A, a row-load command 143 is followed by anactivate-read command 145, which is turn followed by a low-latency readcommand 395 and then a precharge command 149. As shown, because nosubpage activation occurs in response to low-latency read command 395, asubstantially shorter column latency (t_(CAC)) applies in comparison tothe t_(RCD-Y)+t_(CAC) column latency of activate-read command 145.Accordingly, instead of being transmitted a t_(CC) interval after theactivate-read command, transmission of the low-latency read command maybe delayed by the t_(RCD-Y) interval relative to notional activate-readcommand 394 and thus to a substantially later time (i.e., clock cycle 10instead of clock cycle 3 in the example shown), thereby freeing commandbandwidth in the intervening time interval to permit transmission ofother command types. This result may be particularly beneficial in caseswhere the memory access pipeline is interrupted for some number of clockcycles following transmission of activate-read command 145, as thelow-latency read command may be issued at the time shown to maintaindata output continuity (i.e., data bursts 146 and 396 are outputback-to-back as shown) despite the interruption. Thus, theactivation-differentiated command sequence may be sent as an alternativeto a non-differentiated command sequence (with implicit non-activationAR command 394 shown notionally to emphasize the timing differences)when circumstances warrant and vice-versa. In either case, prechargecommand 149 may be advanced by a t_(CC) interval relative to amulti-activation command sequence, thus shortening the net intra-bankrow-to-row latency (t_(RC)) as explained in reference to FIG. 7A. Asecond exemplary command sequence bearing a low-latency read command 401(i.e., following row-load command 163 and activate-read command 165 andyielding data output 402) is shown without the notional activate-readcommand.

FIG. 10B illustrates an example of a closed-page command sequence inwhich row-load and activate-read commands (143, 145) are followed by anauto-precharging low-latency read command 397 (i.e., RP Ca1). As shown,low-latency read command 397 is transmitted at a delayed time (i.e.,t_(RCD-Y)+t_(CC)) relative to activate-read command 145 in accordancewith the non-activating column latency (CL=t_(CAC)), and triggers aprecharge operation after an interval t_(RDP)−t_(CC) (shown by notionalprecharge command 399) on the assumption that an activate-read commandwas issued the shortest possible time earlier (i.e., t_(RCD-Y)+t_(CC)),thus establishing a net delay of at least t_(RCD-Y)+t_(RDP) between thestart times of subpage sense operation 182 and the precharge operation187. As in the command sequence of FIG. 10A, the advanced prechargetiming (i.e., starting the precharge early on the awareness that thesubpage last opened was activated in response to an earlieractivate-read command) shortens the t_(RC) latency relative to protocolsthat do not account for non-activating commands.

Still referring to FIG. 10B, it should be noted that an equivalenttransaction and timing profile may be effected by issuing anactivate-read-precharge command in place of activate-read command 145,and issuing a low-latency read command (e.g., command 395 in FIG. 10A)in place of low-latency read-precharge command 397. In that case, anexplicit non-activation read command is still transmitted at the delayedtime shown, thus providing the benefits described above with respect toFIG. 10A, but no non-activating read-precharge command type need be sentor even included within the memory system command types.

FIG. 11 illustrates three additional command types that may be supportedwithin a deferred-activation memory system, including an additional rowcommand, “Load-Precharge,” and two additional activation-triggeringcolumn commands, “PrechargeDelay-Activate-Read” and“PrechargeDelay-Activate-Read-Precharge.” The load-precharge commandtriggers the same pre-selection operation as the row-load commanddiscussed above, and additionally triggers a bank precharge operationconcurrently with or prior to the pre-selection operation, and thus maybe viewed as a bank-precharging, row-load command. As explained withrespect to the protocol diagrams shown in FIGS. 13A-13C, triggeringprecharge and pre-selection operations with a single command reducescommand bandwidth consumption while maintaining an open-page accesspolicy, as no explicit precharge command need be sent (reduced commandbandwidth), and yet the bank precharge decision may be deferred untilreceipt of a request to access a row of memory other than the one forwhich one or more subpages are open. Thus, the benefits ofauto-precharge are obtained (less command bandwidth) without requiring aclosed-page access policy.

Still referring to FIG. 11 , the additional column commands aresubpage-activating read (or write) commands, one with auto-precharge(PARP) and one without (PAR), that instruct the memory component todelay for a pre-activation interval, t_(RP)−t_(RCD-X), before initiatinga subpage activation, thus permitting time for the precharge operationinitiated by a preceding load-precharge command to complete beforecommencing subpage activation.

FIG. 12 illustrates additional open-page command sequences 405, 407,409, 411 and transitional command sequences 413, 415, 417, 419, 421(i.e., transitioning from an open-page access to a closed-page access orvice-versa) made possible by the additional load-precharge command andthe pre-activation-delay column commands, together with the twoopen-page command sequences and two closed-page command sequencesdescribed in reference to FIG. 9 . Each of the additional open-pagecommand sequences begins with a load-precharge command (LP), thusinitiating a precharge operation with respect to an address specifiedbank, followed or accompanied by a pre-selection operation to assert toan address-specified global word line and corresponding sense amp stripeenable signals within that bank. In one embodiment, the pre-selectionoperation is carried out in the final clock cycle of the prechargeinterval, thus hiding time required to perform the pre-selectionoperation under the precharge interval. In an alternative embodiment,the pre-selection operation is carried out at an earlier time withrespect to the precharge interval (e.g., at the beginning or middle ofthe precharge interval). In either case, the subpage latches are resetas part of the precharge operation so that subsequent assertion of anaddress-specified global word line and sense amp stripe enable signalsdoes not interfere with the precharge operation. In an alternativeembodiment, the pre-selection operation may be deferred until completionof the precharge operation so that the two operations are carried outsequentially rather than in parallel.

Still referring to FIG. 12 , the load-precharge command in each newopen-page command sequence is followed by a non-precharging,precharge-delay column command (PAR) that initiates, after a prechargedelay interval (t_(RP)), a subpage activation operation and then acolumn access (read or write). As shown, the pre-activation-delay columncommand is followed by one or more additional pre-activation-delaycolumn commands (PAR) in command sequences 405 and 409. An ensuingopen-page command sequence may then begin with either an explicitprecharge operation (thus transitioning from a command sequence thatbegins with a combined load-precharge command to one that begins with anexplicit precharge command) or by another load-precharge command.Alternatively, because the pre-activation-delay column command triggersa subpage activation, the pre-activation-delay column command may befollowed by one or more non-activating column commands (i.e., read orwrite commands directed to the open subpage) as shown in commandsequences 407 and 411, with the ensuing command sequence beginning witheither an explicit precharge command or another load-precharge command.

Still referring to FIG. 12 , the transitional command sequences includeopen-page to closed-page transitions that begin with a load-prechargecommand (thus concluding an open-page command sequence) and terminatewith an auto-precharge column command (thus establishing a closed-pagesequence) as well as closed-page to open-page transitions that beginwith a row-load command, but conclude with a load-precharge command (theassumption being that the row-load command is applied instead of theload-precharge command due to conclusion of the preceding commandsequence by an auto-precharging column command, though this need not bethe case).

In each of the open-page to closed-page transitional sequences 417, 419,421, the load-precharge command (LP) is followed by apre-activation-delay column command (PARP or PAR), including a firstsequence 417 in which an auto-precharging pre-activation-delay columncommand (PARP) is followed by an optional pre-activation-delay columncommand (PAR). That is, the PARP command is issued on the determinationby the controller component that the ensuing PAR command, if any, isdirected to the same subpage as the PARP command and thus will triggerno new subpage activation (i.e., constitutes an implicit non-activationcolumn command due to the subpage address match with respect to thepreceding PARP command), thus permitting a shortened t_(RC) cycle. Inthe other open-page to close page command sequences 419 and 421, anon-precharging pre-activation delay command (PAR) is issued followingeach load-precharge to initiate a deferred subpage activation (i.e.,triggering the subpage activation after a t_(RP) delay less a t_(CK)),followed either by an optional number of additional PAR commands(sequence 419) or by an optional number of low-latency column commands(sequence 421). In the examples shown, sequence 419 is concluded by anauto-precharging pre-activation delay command (PARP), and sequence 421is concluded by an auto-precharging non-activating column command (RP).

Closed-page to open-page transitional sequence 413 is similar to theopen page command sequence described in reference to FIG. 3 , exceptthat, instead of an explicit precharge command, a load-precharge command(LP) is issued to trigger both a precharge operation for the subjectcommand sequence and a row-load operation for a subsequent commandsequence. Similarly, transitional sequence 415 is akin to open pagecommand sequence 391 described in reference to FIG. 9 , except insteadof an explicit precharge command, a load-precharge command (LP) isissued to trigger both a precharge operation for the subject commandsequence and a row-load operation for a subsequent command sequence.

FIG. 13A illustrates an exemplary open-page memory protocol employing aload-precharge command. After an initial row-load command 143 andactivate-read commands 145, 147 yield a pair of open subpages (andcorresponding read data transmissions, 146 and 148), load-prechargecommand 423 is issued during the command transmission interval otherwiseoccupied by an explicit precharge command (i.e., shown notionally at424) to precharge the address-specified bank and also to schedule arow-load operation. Accordingly, the bank is precharged over intervalt_(RP), and the row-load operation is carried out immediatelythereafter, as though a load command (shown notionally at 429) wasreceived during the final clock cycle of the precharge interval. Asexplained, this arrangement lowers the overall command/address bandwidthconsumption of open page transactions as no explicit precharge operationneed be transmitted.

Still referring to FIG. 13A, because load-precharge command 423 triggersa deferred row-load execution (i.e., schedules the pre-selectionoperation for execution at the conclusion of the bank precharge, thoughsuch execution may be carried out earlier as discussed), subpageactivation operations are similarly deferred. Thus, a t_(RCD-X) intervalafter transmission of load-precharge command 423, an initialprecharge-delayed column command 425 is transmitted to triggert_(RP)-delayed activate-read operations corresponding to notionalactivate-read command 431 (i.e., deferred execution of subpageactivation and column read operations are carried out as though inresponse to an activate-read command received at the time shown bynotional command 431) and thus output of read data 426 (Q(Cc0)) after atotal column latency of t_(RP)+t_(RCD-Y)+t_(CAC). A t_(CC) intervalafter transmission of command 425, a second precharge-delay columncommand 427 is transmitted, again to trigger t_(RP)-delayedactivate-read operations (i.e., activate-read executed at a timecorresponding to notional activate-read command 433) and thus dataoutput at 428 (Q(Cd0)). In effect, the subpage activation operations aretwice-deferred (double-delay) relative to load-precharge command 423,with a first deferral to provide time for the bank precharge operationto complete, and a second deferral according to the pre-activation delayt_(RCD-X) between receipt of the load-precharge command and thepre-activation delay column command 425. As explained above, the tRCD-Xinterval may arbitrarily long, though shown as a single clock cycle.

Still referring to FIG. 13A, it should be noted that precharge-delaycolumn commands 425, 427 may be replaced by non-t_(RP)-delayingactivate-read commands in an alternative command protocol. That is, thecontroller component could transmit activate-read commands at the timeshown by notional commands 431 and 433 instead of the precharge-delaycolumn commands shown. Also, in an alternative embodiment, the row-loadoperation triggered by load-precharge command 423 may be executed duringthe bank precharge and thus during the t_(RP) interval instead of afterthe t_(RP) interval as shown by the bank precharge and pre-selectionoperations 187, 190 within the core activity timeline. In such anembodiment, which is reflected by the timing descriptions within thecommand table of FIG. 11 , the preactivation-delay corresponding toprecharge-delay column commands 425, 427 may be reduced by as much ast_(RCD-X) and thus to t_(RP) less t_(RCD-X). In such an embodiment, theactivate-read operations triggered by the precharge-delay columncommands are advanced by t_(RCD-X) (a clock cycle in the example shown),thus reducing the overall access latency with respect to theload-precharge command, shortening the t_(RC) interval by t_(RCD-X).

FIG. 13B illustrates an alternative command sequence that employs aload-precharge command to reduce CA bandwidth consumption, and in whicheach subpage-activating column command (441, 451) triggers output of twobursts of data (442 a/442 b, 452 a/452 b) from respective address ranges(e.g., column address ‘a’ and address ‘a+x’, and ‘b’ and ‘b+x,’ where‘x’ is the burst length multiplied by the data I/O width). As shown, thedouble-burst output further reduces CA bandwidth consumption by halvingthe number of column commands required to generate data output over twosuccessive t_(CC) intervals. Accordingly, only two commands need beissued to access data within a given bank, while maintaining anopen-page policy and thus the option to access additional subpagesand/or additional columns within a previously opened subpage. Whileshown in the context of a command sequences initiated by load command143, and load-precharge command 423, column commands that triggerdouble-burst outputs may be employed in any other command sequencespossible under embodiments disclosed herein. Also, the double-burst maybe signaled by the column command itself (e.g., via a field of one ormore bits that indicates one of a number of possible multipliers to beapplied to a burst length value programmed within a mode register of thememory component, or via a field of one or more bits that directlyindicate the burst length), or by a value programmed within aconfiguration register or mode register of the memory component.

FIG. 13C illustrates another exemplary open-page memory protocolemploying a load-precharge command, in this case followed by anauto-precharging column command and then a non-activating columncommand. More specifically, a precharge-delay, auto-precharging columncommand (PARP) 455 is transmitted immediately after the load-prechargecommand 423, thus triggering t_(RP)-deferred actions corresponding tonotional auto-precharging activate-read command (ARP) 461. A t_(CC)interval after transmission of PARP command 455, a non-auto-prechargingpre-activation delay column command 457 (PAR) bearing a column addressthat resolves to the subpage activated by the preceding PARP command, istransmitted to trigger an access to the open (or opening) subpage.Because PAR command 457 hits the open subpage, no second subpageactivation is triggered within the command sequence shown (i.e., PARcommand is an implicitly non-activating column command) so that asubpage-aware controller may transmit an ensuing load-precharge command464 a t_(CC) interval earlier than possible if a second subpageactivation was triggered (or if the controller component was unawarewhether a second subpage activation was triggered or not), and thusearlier than shown in the protocol of FIG. 13A. As shown, the columnlatency described in reference to FIG. 13A applies, with read data 456(Q(Cb0)) and 458 (Q(Cb1)) being output after column latencyt_(RP)+t_(RCD-Y)+t_(CAC) relative column commands 455 and 457,respectively. Also, precharge-delay column command 457 yields columnaccess operations as though implemented by notional non-activatingcolumn command 463.

FIG. 13D illustrates another exemplary open-page memory protocolemploying load-precharge command 423, in this case followed by anon-auto-precharging precharge-delay column command 425 and then by alow-latency, non-activating column command 465. The protocol shown issimilar to that of FIG. 13D, except that the non-auto precharging columncommand establishes an open-bank command sequence, and the low-latencycolumn command need not be issued until the time shown (a t_(CAC)interval prior to the desired data output time instead of the time shownby notional activate read command 467), thus providing the low-latencyaccess benefits described above.

FIG. 14 illustrates embodiments of a controller component 501 and memorycomponent 503 that may be used to implement the variousdeferred-activation command sequences and protocols described above.Memory component 503 includes seven banks 541 ₀-541 ₇ in the exampleshown (more or fewer banks may be provided in alternative embodiments),together with command/address (CA) logic 543, CA receiver 543, dataserializing/deserializing logic 545, data output driver 551 and datareceiver 549. Controller component 501 includes a transaction queue 511coupled between a host interface 510 and memory command and datainterfaces. The memory command interface includes optional CAserializing logic 513 and a CA output driver 517, the latter coupled toits memory component counterpart (i.e., CA receiver 547) via one or moreCA signaling links 502. The memory data interface includes a datatransceiver (formed by data output driver 519 and data receiver 521)coupled to the memory component data transceiver (549 and 551) via oneor more data (DQ) links 504, and serializing/deserializing logic 515coupled between the data transceiver and transaction queue 511 toserialize outgoing write data for transmission via a relatively narrowdata path (i.e., enabling a quantum of data containing a number of bitsgreater than the number of data signaling links to be subdivided andtransmitted in sequential transmit intervals) and, conversely, todeserialize incoming read data.

Controller component 501 receives memory transaction requests from oneor more host requestors (e.g., a general purpose single-core ormulti-core processor, a graphics processor, a digital signal processor,a direct-memory-access (DMA) controller, etc.) via host interface 510and stores the transaction requests within transaction queue 511.Transaction queue 511 includes logic to convert the incoming transactionrequests into memory command sequences which are queued for transmissionto memory component 503 via CA path 502 in accordance with the variousprotocol options and embodiments described above. In the case of writetransaction requests, corresponding write data values are also receivedvia host interface 510 and queued within transaction queue 511 fortransmission via the data path (i.e., DQ links 504) at predeterminedtimes relative to transmission of corresponding command sequences thatinstruct storage of the write data. Conversely, in a read transactionrequest, read data returned by memory component 503 via DQ links 504 isorganized within transaction queue 511 for return to the source of theoriginal transaction request via host interface 510. Though only asingle transaction queue is shown within controller component 501,multiple transaction queues 511 may be provided to manage memory accesstransactions with respect to corresponding memory components orindependently controllable subsections of a memory component, eachtransaction queue controlling command and data transfer over arespective memory channel (e.g., formed by additional sets of CA links502 and DQ links 504).

In the embodiment shown, transaction queue 511 includes a configurationregister 523 that may be programmed in accordance with operationalcharacteristics of memory component and memory application requirements.Thus, deferred activation (dAct), variable column latency (i.e.,vCL—command differentiated column latency), precharge-delay protocols(dPrchg), multi-burst (i.e., BL—data output over two or more t_(CC)intervals) and any other protocol and command options disclosed hereinmay all be enabled or disabled and tailored according to applicationrequirements and memory component capability by programming respectivecontrol fields within configuration register 523. Further, variouscontrol fields may be programmed to establish delay intervals, such asthe time between row-load and an initial subpage-activating columncommand (t_(RCD-X)) within a given command transaction, the time betweensubpage activation and column access (t_(RCD-Y)), various latencyparameters and so forth. In an embodiment having multiple transactionqueues, a single configuration register 523 may be used to establishtransaction conversion options (i.e., conversion of host request tomemory command sequence) and command-to-command timing parameters (e.g.,t_(RCD-X), t_(RCD-Y), etc.) across all transaction queues, or respectiveconfiguration registers 523 may be provided within (or otherwisededicated to) each transaction queue to enable transaction protocols andparameters to be varied from queue to queue.

Command/address values received within memory component 503 (i.e., viaCA links 502 and CA receiver 547) are decoded within CA logic 543 toyield bank, row and column control signals (CA-B and CA-R and CA-C,respectively) which are forwarded to the memory banks. In oneembodiment, the bank control signals constitute a bank address thatenables latching circuitry within the command-specified bank to receiverow-control signals or column-control signals as the command mayindicate. In the case of a row-load command directed to bank 0, forexample, CA logic 543 outputs the row address received in connectionwith the command onto the row-control lines (CA-R), and outputs a bankcontrol signal indicating a row-load operation together with the bankaddress (i.e., received in connection with the row-load command) ontothe bank-control lines (CA-B). In combination, the bank address and bankcontrol signal enable the row address to be latched within the rowdecoder for bank 0 (i.e., raising a row-address-strobe (RAS) signalwithin bank 0), thereby triggering the pre-selection actions describedabove within the address-specified bank. As another example, CA logic543 responds to a subpage-activating column command by outputting thecolumn address received in connection with the command onto thecolumn-control lines (CA-C), and outputting a bank control signalindicating the nature and timing of the column operation (e.g., whethera read or write is to be executed and, optionally, the column latency tobe effected within the column access pipeline logic) and that, togetherwith a bank address, enables the column address to be captured withinthe column access pipeline logic (e.g., element 311 of FIG. 6A) andenables a subpage latching operation within the subpage decode/activatelogic and subpage stripe latches (e.g., elements 305 and 315 of FIG.6A). More generally, CA logic 543 issues control signals to the row andcolumn logic circuitry within an address specified bank (541 ₀-541 ₇) tocarry out the commanded operations generally as described above withrespect to various row and column operations.

In the embodiment shown, memory component 503 includes a mode register544 that may be programmed by controller component 501 (or by anotherdevice, for example, during component production) to control operationalaspects of the memory component, including without limitation, subpagesize, burst length, delays associated with deferred subpage activation,command-differentiated column latencies (e.g., t_(RCD-X), t_(RCD-Y),CL1, CL2) and so forth. The values programmed within mode register 544may be applied by CA logic 543 to establish the combination and timingof bank, row and/or column control signals to be asserted in response toa given command and thus enable operations within memory component 503as described above in reference to timing, protocol and logic diagramscorresponding to various embodiments.

The subpage activate/decode logic (e.g., logic 255 of FIG. 5A) can beprovisioned to support other addressing features. For instance, a memorycontroller may specify a range of subarray granularities, either bysetting a mode register or explicitly indicating a mode in a command. Atthe finest supported granularity, each subarray is independentcontrolled using the MSBs of a supplied column address. At highergranularities (i.e., coarser granularities), multiple subarrays (e.g.,2, 4, etc., up to an entire row) are activated at once by applying fewerMSBs of a supplied column address. This feature can be used for afull-row refresh, where all subarrays are triggered simultaneously for arefresh operation. Alternatively, a reduced-peak-power refresh operationmay be supported, where the subpage activate/decode logic automaticallystaggers the activate signals to different subarrays in the refreshedrow, providing a slightly longer refresh operation with potentialsignificant savings in peak power demanded for refresh.

While a single memory component 503 is shown in FIG. 14 , numerousmemory components 503 may be provided in alternative embodimentsemploying various interconnection topologies. For example, sets ofmemory components 503 may be disposed on respective memory modules(e.g., substrates having packaged or bare-die memory components disposedthereon as in the case of a dual-inline memory module or DIMM) that areremovably inserted within sockets connected via printed-circuit-boardtraces to controller component 501. The set of memory components 503disposed on a given memory module may include one or more groups or“ranks” of memory components in which the constituent memory componentsof each rank are coupled to controller component 501 via a shared CApath and via respective data paths, thus enabling the rank of memorycomponents to be accessed in parallel (concurrently) as though a unifieddevice. In an alternative embodiment, memory components 503 implementedon respective integrated circuit dies may be combined, with or withoutcontroller component 501, within an integrated circuit package, such asa system in package or multi-chip package (SIP, MCP) or within groups ofpackages such as package-in-package or package-or-package (PIP, POP)arrangements. In all such cases, the interconnections between thecontroller component and memory components may be effected by virtuallyany wired or wireless signal conveyance scheme, including printed wireboard traces, bond wires, flex cables (or any other cabling mechanisms),through-silicon-vias (TSVs), inductive or capacitive interconnects andso forth.

Controller component 501 may be a dedicated memory controller (i.e., apackaged or unpackaged IC die designed primarily for the purposes ofproviding an interface between one or more attached memory componentsand a processor, DMA and/or another integrated circuit device within ahost system), or may constitute part of a processor,application-specific IC (ASIC) or other device that performs functionsbeyond memory access and control. In either case, a number of thecontroller component actions described herein may instead be carried outby a programmed processor (or dedicated hardware or combination ofhardware and programmed processor), with results or instructions arisingfrom those actions issued to the controller component as a set ofcommands.

FIG. 15 illustrates a sequence of configuration operations that may beexecuted by the controller component of FIG. 14 to enable thedeferred-activation operations described above. At 575, the controllercomponent determines the command-execution capability of one or moreattached memory components via a configuration data source (e.g., aserial presence detect (SPD) memory or other non-volatile storage withinor separate from the memory component(s) that contains informationcharacterizing the capabilities of the memory component(s)). At 577, thecontroller component updates fields within one or more configurationregisters (e.g., register 523 of FIG. 14 , or multiple instances of suchregister if provided in association with respective transaction queues)including, for example, selecting between deferred-activation andimmediate-activation command protocols (dAct=1 or dAct=0), enabling ordisabling transmission of column commands having different columnlatencies (vCL=1 or vCL=0), enabling or disabling transmission ofload-precharge commands and corresponding pre-activation delay columncommands (e.g., dPrchg=1 or dPrchg=0, thereby enabling or disablingissuance of commands LP, PAR and PARP as described in reference to FIGS.11, 12 and 13A-13D), enabling or disabling multi-burst output (BL=1 orBL=0), programming t_(RCD-X) and t_(RCD-Y) delays and any other delaysaffecting command and/or data transmission/reception timing and that mayvary from memory component to memory component or in accordance withapplication requirements. At 579, the controller component issuesregister programming commands to the attached memory component(s) inaccordance with the command-execution capability of the attached memorydevices including, for example and without limitation, programming thedata burst length to be output or received in response to asubpage-activating column command, various delay intervals to be applied(t_(RCD-X), t_(RCD-Y), etc.) and/or command differentiated columnlatencies (CL1, CL2). After programming the mode registers withinattached memory components, the configuration operation is deemed to becomplete (though additional calibration or initialization procedures mayapply) and the controller component may begin issuing sequences ofcommands as described above and in accordance with the programmedcontroller component configuration and memory component modes.

It should be noted that the various circuits disclosed herein may bedescribed using computer aided design tools and expressed (orrepresented), as data and/or instructions embodied in variouscomputer-readable media, in terms of their behavioral, registertransfer, logic component, transistor, layout geometries, and/or othercharacteristics. Formats of files and other objects in which suchcircuit expressions may be implemented include, but are not limited to,formats supporting behavioral languages such as C, Verilog, and VHDL,formats supporting register level description languages like RTL, andformats supporting geometry description languages such as GDSII, GDSIII,GDSIV, CIF, MEBES and any other suitable formats and languages.Computer-readable media in which such formatted data and/or instructionsmay be embodied include, but are not limited to, computer storage mediain various forms (e.g., optical, magnetic or semiconductor storagemedia, whether independently distributed in that manner, or stored “insitu” in an operating system).

When received within a computer system via one or more computer-readablemedia, such data and/or instruction-based expressions of the abovedescribed circuits may be processed by a processing entity (e.g., one ormore processors) within the computer system in conjunction withexecution of one or more other computer programs including, withoutlimitation, net-list generation programs, place and route programs andthe like, to generate a representation or image of a physicalmanifestation of such circuits. Such representation or image maythereafter be used in device fabrication, for example, by enablinggeneration of one or more masks that are used to form various componentsof the circuits in a device fabrication process.

In the foregoing description and in the accompanying drawings, specificterminology and drawing symbols have been set forth to provide athorough understanding of the disclosed embodiments. In some instances,the terminology and symbols may imply specific details that are notrequired to practice those embodiments. For example, any of the specificnumbers of bits, signal path widths, signaling or operating frequencies,component circuits or devices and the like may be different from thosedescribed above in alternative embodiments. Additionally, links or otherinterconnection between integrated circuit devices or internal circuitelements or blocks may be shown as buses or as single signal lines. Eachof the buses may alternatively be a single signal line, and each of thesingle signal lines may alternatively be buses. Signals and signalinglinks, however shown or described, may be single-ended or differential.A signal driving circuit is said to “output” a signal to a signalreceiving circuit when the signal driving circuit asserts (or deasserts,if explicitly stated or indicated by context) the signal on a signalline coupled between the signal driving and signal receiving circuits.An address or other value provided “in” or “with” a command may betransmitted concurrently (i.e., at least partly overlapping in time)with a group of bits containing a command code or identifier, orprepended, appended or otherwise transmitted in association with thecommand code or identifier. The term “coupled” is used herein to expressa direct connection as well as a connection through one or moreintervening circuits or structures. Integrated circuit device“programming” may include, for example and without limitation, loading acontrol value into a register or other storage circuit within theintegrated circuit device in response to a host instruction (and thuscontrolling an operational aspect of the device and/or establishing adevice configuration) or through a one-time programming operation (e.g.,blowing fuses within a configuration circuit during device production),and/or connecting one or more selected pins or other contact structuresof the device to reference voltage lines (also referred to as strapping)to establish a particular device configuration or operation aspect ofthe device. The terms “exemplary” and “embodiment” are used to expressan example, not a preference or requirement.

Various modifications and changes may be made to the embodimentspresented herein without departing from the broader spirit and scope ofthe disclosure. For example, features or aspects of any of theembodiments may be applied, at least where practicable, in combinationwith any other of the embodiments or in place of counterpart features oraspects thereof. Accordingly, the specification and drawings are to beregarded in an illustrative rather than a restrictive sense.

What is claimed is:
 1. A method of operation within a dynamic randomaccess memory (DRAM) component, the method comprising: receiving a firstcommand/address value during a first interval, the first command/addressvalue including a row command and row address; decoding the row addressin response to the row command to activate a first global word linecorresponding to a first row of DRAM cells within the DRAM component;receiving a second command/address value during a second interval, thesecond command/address value including a first column command, firstsub-row address and first column address; decoding the first sub-rowaddress in response to the first column command to activate a firstsub-row word line corresponding to a first sub-row of DRAM cells withinthe first row of DRAM cells, enabling conduction of contents of thefirst sub-row of DRAM cells to a first sub-row region of a senseamplifier bank within the DRAM component.
 2. The method of claim 1further comprising storing the contents of the first sub-row of DRAMcells within the first sub-row region of the sense amplifier bank inresponse to the first column command.
 3. The method of claim 2 whereinthe second interval commences a predetermined time after commencement ofthe first interval, and wherein a collective time required to activatethe first sub-row word line, conduct the contents of the first sub-rowof DRAM cells to the first sub-row region of the sense amplifier bankand store the contents within the first sub-row region of the senseamplifier bank exceeds the predetermined time.
 4. The method of claim 2further comprising decoding the first column address in response to thefirst column command to access a column of data within the first sub-rowregion of the sense amplifier bank.
 5. The method of claim 4 wherein thefirst column command specifies a column read operation, and whereinaccessing the column of data within the first sub-row region of thesense amplifier bank comprises outputting the column of data from theDRAM component via a data signaling interface.
 6. The method of claim 4wherein the first column command specifies a column write operation, andwherein accessing the column of data within the first sub-row region ofthe sense amplifier bank comprises receiving a column of write data viaa data signaling interface of the DRAM component and storing the columnof write data within the first sub-row region of the sense amplifierbank.
 7. The method of claim 1 wherein the sense amplifier bankcomprises a plurality of sense amplifiers corresponding, in quantity, toa quantity of DRAM cells that constitute the first row of DRAM cells. 8.The method of claim 7 wherein the first sub-row region of the senseamplifier bank comprises one of a plurality of sub-row regions withinthe sense amplifier bank, each of the sub-row regions constituted by arespective subset of the sense amplifiers.
 9. The method of claim 1further comprising: receiving, while the global word-line remainsactivated in response to the row command, a third command/address valuethat specifies a second column command, second sub-row address andsecond column address; and decoding the second sub-row address inresponse to the second column command to activate a second sub-row wordline corresponding to a second sub-row of DRAM cells within the firstrow of DRAM cells, enabling conduction of contents of the second sub-rowof DRAM cells to a second sub-row region of a sense amplifier bank. 10.The method of claim 1 further comprising executing a precharge operationwith respect to the first sub-row of storage cells in response to thecolumn command after accessing a column of data within the first sub-rowregion of the sense amplifier bank.
 11. A memory component comprising: adynamic random access memory (DRAM) array; a sense amplifier bank; acommand/address signaling interface to receive first and secondcommand/address values during first and second intervals, respectively,the first command/address value including a row command and row address,and the second command/address value including a first column command,first sub-row address and first column address; and control circuitryto: decode the row address in response to the row command to activate afirst global word line corresponding to a first row of DRAM cells withinthe DRAM array; and decode the first sub-row address in response to thefirst column command to activate a first sub-row word line correspondingto a first sub-row of DRAM cells within the first row of DRAM cells andenable conduction of contents of the first sub-row of DRAM cells to afirst sub-row region of the sense amplifier bank.
 12. The memorycomponent of claim 11 wherein the control circuitry comprises circuitryto store the contents of the first sub-row of DRAM cells within thefirst sub-row region of the sense amplifier bank in response to thefirst column command.
 13. The memory component of claim 12 wherein thesecond interval commences a predetermined time after commencement of thefirst interval, and wherein a collective time required to activate thefirst sub-row word line, conduct the contents of the first sub-row ofDRAM cells to the first sub-row region of the sense amplifier bank andstore the contents within the first sub-row region of the senseamplifier bank exceeds the predetermined time.
 14. The memory componentof claim 12 wherein the control circuitry comprises circuitry to decodethe first column address in response to the first column command toaccess a column of data within the first sub-row region of the senseamplifier bank.
 15. The memory component of claim 14 further comprisinga data signaling interface, and wherein the first column commandspecifies a column read operation, and wherein the circuitry to accessthe column of data within the first sub-row region of the senseamplifier bank comprises circuitry to output the column of data from thememory component via the data signaling interface.
 16. The memorycomponent of claim 14 further comprising a data signaling interface, andwherein the first column command specifies a column write operation, andwherein the circuitry to access the column of data within the firstsub-row region of the sense amplifier bank comprises circuitry toreceive a column of write data via the data signaling interface and tostore the column of write data within the first sub-row region of thesense amplifier bank.
 17. The memory component of claim 11 wherein thesense amplifier bank comprises a plurality of sense amplifierscorresponding, in quantity, to a quantity of DRAM cells that constitutethe first row of DRAM cells.
 18. The memory component of claim 17wherein the first sub-row region of the sense amplifier bank comprisesone of a plurality of sub-row regions within the sense amplifier bank,each of the sub-row regions constituted by a respective subset of thesense amplifiers.
 19. The memory component of claim 11 wherein thecommand/address signaling interface is further to receive a thirdcommand/address value while the global word-line remains activated inresponse to the row command, the third command/address value specifyinga second column command, second sub-row address and second columnaddress, and wherein the control circuitry to decode the first sub-rowaddress in response to the first column command additionally decodessecond sub-row address in response to the second column command toactivate a second sub-row word line corresponding to a second sub-row ofDRAM cells within the first row of DRAM cells and enable conduction ofcontents of the second sub-row of DRAM cells to a second sub-row regionof a sense amplifier bank.
 20. A memory component comprising: a dynamicrandom access memory (DRAM) array; a sense amplifier bank; means forreceiving first and second command/address values during first andsecond intervals, respectively, the first command/address valueincluding a row command and row address, and the second command/addressvalue including a first column command, first sub-row address and firstcolumn address; and means for: decoding the row address in response tothe row command to activate a first global word line corresponding to afirst row of DRAM cells within the DRAM array; and decoding the firstsub-row address in response to the first column command to activate afirst sub-row word line corresponding to a first sub-row of DRAM cellswithin the first row of DRAM cells and enable conduction of contents ofthe first sub-row of DRAM cells to a first sub-row region of the senseamplifier bank.